106 ANTIGENS AND ANTIBODIES 



them with the precipitins, while others look upon them as a peculiar 

 type of lysins, which may accordingly be termed albuminolysins, 

 and suppose that during the interaction between the lysin and its 

 antigen, at the time of the second injection, highly poisonous inter- 

 mediary products are formed to which the peculiar symptoms are 

 in turn due. 



Anaphylaxis. As the injected animal has evidently become more 

 sensitive to the action of the foreign albumin than it was before the 

 first injection, which usually does not give rise to any serious symp- 

 toms, Richet suggested the term anaphylaxis to express this condition 

 of hypersusceptibility, in contradistinction to prophylaxis, diminished 

 susceptibility or immunity, in the older sense of the word. This 

 term has now been generally accepted, and the more or less threaten- 

 ing symptoms w y hich follow the second injection are accordingly 

 spoken of as the anaphylactic shock. French writers, more particu- 

 larly, refer these symptoms to a special anaphylactic reaction product 

 which they term anaphylactin. v. Pirquet, as we have already seen, 

 has introduced the non-committed term allergia to denote the changed 

 mode of reaction on the part of the injected animal (no matter what 

 antigen has been used) and speaks of the antigenic substances as 

 the alhrgins and the reaction products as the corresponding ergins. 

 According to his ideas, anaphylaxis is thus merely one form in which 

 the general allergia can express itself. In a subsequent chapter we 

 shall have occasion to deal with this problem in greater detail, and 

 we hope to show that the antibodies which are especially involved 

 in the anaphylactic reaction, play an important role in the symptom- 

 atology of many diseases. 



Protective (defensive) Ferments. The most recent discovery in the 

 domain of antibody formation, finally, we owe to the genius of Abder- 

 halden. This investigator showed that whenever complex (non- 

 denatured) foodstuffs are introduced into the body by parenteral 

 channels, corresponding ferments appear in the circulation which 

 are capable of bringing about the cleavage of the bodies in question. 

 This occurs, however, not only when the foodstuffs are derived from 

 an alien source, but also when products of this order w r hich are nor- 

 mally foreign to the blood enter the blood from the body itself. 

 Abderhalden could thus show that during pregnancy, when chorion 

 cells or chorion cell proteins are known to enter the circulation, a 

 proteolytic ferment appears in the blood which is specifically directed 



